The present invention relates to a rotary laser irradiating system for irradiating and rotating a laser beam at the same time and for forming a reference plane by the laser beam, and in particular, to a rotary laser irradiating system capable to form, in addition to a horizontal reference plane, a tilt setting plane tilted at a predetermined angle with respect to the horizontal reference plane.
A rotary laser irradiating system irradiates and rotates a laser beam toward a plane that is used as a reference and forms a reference plane by the laser beam. When the laser beam scans across a wall surface or the like, a locus of the laser beam is turned to a reference line on the reference plane. Therefore, in case the reference plane is a horizontal plane, the reference line is horizontal, and the height of the reference line is equal to the height of the reference plane, and the reference line is used as a reference for horizontality or height. By tilting a rotation axis of the laser beam, it is possible to form a reference plane tilted with respect to the horizontal plane. The tilt reference plane is used for positioning of a tilt plane for construction work in civil engineering, architectural engineering, etc.
The rotary laser beam irradiating system is vertically installed at a predetermined position or at a position used as a reference such as a reference point via a special-purpose stand or a tripod. As described above, the rotary laser irradiating system irradiates the laser beam in a horizontal direction and rotates it to form a horizontal reference plane. By tilting a rotation axis of the irradiated laser beam, a tilt reference plane is formed. Because the rotary laser irradiating system is used to form a horizontal reference plane or a tilt reference plane, it is provided with a high-accuracy tilt setting function to tilt the reference plane. Referring to FIG. 6, description will be given below on a conventional type rotary laser irradiating system.
FIG. 6 shows an essential mechanism of a rotary laser irradiating system 1. The rotary laser irradiating system 1 comprises a light emitter 2 for accommodating a light emitting element and an optical system and for emitting laser beam, a rotator 3 rotatably mounted on the light emitter 2 and irradiating and rotating the laser beam within a reference plane, tilt setting units 4 for performing leveling of the rotary laser irradiating system 1 and for setting tilt of the reference plane, and a tilt detecting unit 5 for detecting tilt of the rotary laser irradiating system 1 and a tilt angle of the light emitter 2.
On a part of the light emitter 2, a spherical unit 6 is formed, and the spherical unit 6 is tiltably supported on a receiving seat 7 (or gimbals), which has a spherical projection. On the upper end of the light emitter 2, the rotator 3 is rotatably mounted. A scanning gear 8 is fitted on the rotator 3, and the scanning gear 8 is engaged with a driving gear 11 of a scanning motor 9 provided on the light emitter 2. When the driving gear 11 is driven, the rotator 3 is rotated. The rotator 3 comprises a pentagonal prism 13, which reflects the laser beam emitted from the light emitter 2 and deflects it in a horizontal direction. By the pentagonal prism 13, the laser beam 14 is projected in a horizontal direction.
From the light emitter 2, two tilting arms 12 (one of them is not shown) are extended in a horizontal direction. The two tilting arms 12 and 12 cross each other perpendicularly and are connected respectively to the tilt setting units (one of them is not shown) as to be described later.
Description is now given on the tilt setting unit 4.
A tilting motor 16 mounted on the casing 15 of the rotary laser irradiating system 1 is connected to a tilt setting screw 18 via a gear train 17. On the tilt setting screw 18, a slide nut 19 is screwed, and the slide nut 19 is engaged with the tip of the tilting arm 12. When the tilting motor 16 is driven, the tilt setting screw 18 is rotated via the gear train 17. The slide nut 19 is moved up or down, and the light emitter 2 is tilted via the tilting arm 12. By two sets of the tilt setting units 4, tilt of the light emitter 2 can be set in any direction as desired.
Tilt angle of the light emitter 2 is detected by the tilt detecting unit 5 mounted on the lower end of the light emitter 2. The tilt detecting unit 5 comprises two tilt sensors 22 and 23 crossing each other perpendicularly and a tilt amount calculating unit (not shown) for detecting tilt of the light emitter 2 based on output signals from the tilt sensors 22 and 23. The driving of the tilting motor 16 is controlled according to the output from the tilt detecting unit 5. Tilt setting is achieved by driving the tilting motor 16 at an angle, which is converted to the number of pulses.
In the conventional type rotary laser beam irradiating system as described above, when the tilt setting unit 4 is driven for performing tilt plane setting and the light emitter 2 is tilted at a predetermined angle, the light emitter 2 is tilted around the center O of the spherical unit 6. Thus, as shown in FIG. 7, after the tilt setting of the pentagonal prism 13 (FIG. 7 (A)), the center is displaced from its position before the tilt setting (FIG. 7 (B) ) by an amount of a horizontal displacement .DELTA.H and by an amount of a vertical displacement .DELTA.V. The vertical displacement .DELTA.V is turned to an error in height of the reference plane, but it is small in value and can be easily compensated, and it causes no substantial problem. However, the horizontal displacement .DELTA.H is an error which is large in value and may cause considerable deviation from the reference point already determined. Therefore, problems may arise in case a distance is measured using the irradiated laser beam or in case the measured value is used.